Escherichia coli O157: infection and infection prevention through hygiene in the home October 2008

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1 Escherichia coli O157: infection and infection prevention through hygiene in the home October 2008 This leaflet has been put together to provide background information and advice on what to do if there is a risk of spread of E. coli O157 in the home. This briefing material has been produced for those who work in the healthcare professions, the media and others who are looking for some background understanding of hygiene issues related to E. coli O157 and/or those who are are responsible for providing guidance to the public on coping with hygiene issues associated with E. coli O157. What is E. coli O157? E. coli O157 is one of hundreds of strains of the bacterium Escherichia coli. Although most strains of E. coli are harmless and live in the intestines of healthy humans and animals, this particular strain produces a powerful verocytotoxin, a poison that plays a part in making the bacteria so harmful, causing severe illness. It is sometimes referred to as verocytotoxin producing E. coli (VTEC) or enterohaemorrhagic E.coli (EHEC). E. coli O157 was first recognised as a cause of illness in 1982 during an outbreak of severe bloody diarrhoea; the outbreak was traced to contaminated hamburgers. E. coli O157 can cause a range of symptoms from mild diarrhoea to bloody diarrhoea (haemorrhagic colitis). Haemorrhagic colitis is often accompanied by severe abdominal cramps but usually without fever. The incubation period for infection before the onset of diarrhoea can range from 1 to 14 days. Symptoms usually resolve within two weeks. Where is E. coli O157 found? Over 15% of healthy cattle may carry E. coli O157 in their gut. Animals are usually unaffected, although a few may become ill. Meat can become contaminated during slaughter, and organisms can be thoroughly mixed into beef when it is ground. Bacteria present on the cow's udders or on equipment may get into unpasterised milk. The organism has also been isolated from 7% of sheep, and there are reports of it being isolated from other animals. E. coli O157 is also found in the gut and faeces of people who have become infected. In some cases people can act as symptomless carriers

2 How does E. coli O157 get into the home? Through contaminated raw meat and unpasteurised milk - studies showed that 0.4%-0.8% of raw meat products purchased from UK butchers were positive for E. coli O157. Through cooked meat products such as sausages and pies which have become cross-contaminated from raw contaminated foods on the premises due to poor hygiene practices. Through fresh vegetables which have become contaminated from raw contaminated sewage or contaminated water. Farm animal faeces are a high risk source of E. coli O157: Family members can pick up the organism during visits to animal exhibits e.g. farms and petting zoos. An infected family member may act as the primary source of infection in the home. How do people become infected? E. coli spreads via the common routes for stomach bugs. It enters the body to infect the gastrointestinal tract via the mouth. It gets into the mouth via contaminated food or hands and sometimes via water (although water contamination is unusual in the UK) Food can be contaminated with E.coli O157 because it has not been properly cooked or properly stored, or because, after cooking, it has been contaminated from dirty hands or contact with contaminated raw food. Hands can be contaminated in a whole variety of ways such as visiting the toilet, handling contaminated food or touching a surface which has been touched by someone else with contaminated hands. The hands can also become contaminated by direct contact with animals or their faeces during farm visits This means that: 1. Foodborne (or waterborne) infection can occur by: Eating undercooked meat especially minced beef produced as burgers. Drinking unpasteurised milk, or milk that has been contaminated after pasteurisation. Drinking water supplies contaminated with faeces; this is more likely to occur with private supplies. Eating unwashed, unpeeled vegetables or fruit fertilised with infected manure. Direct or indirect cross-contamination from contaminated raw food (e.g. poultry) to other food which may be eaten without further cooking, e.g. salads. Infected food handlers (who may have no symptoms of illness) can contaminate food during preparation and handling. Outbreaks have been associated also with other foods: yoghurt, cooked meats, meat pies, cheese, dry cured salami, raw vegetables, unpasteurised apple juice and water. Current data indicates that eating contaminated (usually undercooked) ground beef is still the single most important cause of foodborne E. coli O157 illness. However, leafy green vegetables are the second most significant cause as they are subject to contamination and they are eaten raw. In a US study, of 23 patients infected with E. coli 0157, 80% of the cases were thought to have originated from consumption of Page 2/8

3 hamburgers in the home and food preparers in those homes were significantly less likely to report washing their hands or work surfaces. The transmission was believed to have occurred more often when the hands of food preparers were allowed to cross-contaminate other food and utensils 2. Person-to-person spread of infection: Person-to-person contact in families, nurseries, and infant schools is an important mode of transmission. Bacteria in diarrhoeal stools of infected persons can be passed from one person to another if hygiene or handwashing habits are inadequate. This is particularly likely among toddlers who are not toilet trained. Family members and playmates of these children are at high risk of becoming infected. EHEC/VTEC strains, including O157, readily transmit in the home to cause secondary infections because their infectious dose is very low (maybe as few as 10). In a study carried out in Wales secondary transmission from an infected person to another family member in the home is estimated at 4-14% 3. Infection associated with visits to farms and other animal exhibits Family members can pick up the organism on their hands and then transfer the organisms directly from hand to mouth during visits to animal exhibits e.g. farms. Indirect contact with infected animals, e.g. via domestic animals such as dogs or cats, and via items of clothing contaminated with cattle faeces can also lead to infection. Incidence of E. coli O157 infections The highest incidence of reported cases occurs in children. In addition to children, the elderly are known to be susceptible to E. coli O157 infection. While these populations are more susceptible to illness, people of all ages can suffer infection from E. coli O157. Reports of haemorrhagic colitis infections are uncommon, but this is probably not reflective of their true frequency. Due to unmistakable symptoms of visible blood in severe cases, these victims usually seek medical attention, but less severe cases are probably more numerous. Hospitalisation is a common occurrence with E. coli O157 infection. It is estimated there are 2,100 hospitalisations annually in the United States. The 2006 European Community Summary Report on foodborne infections reported a total of 4,916 confirmed cases of verotoxigenic Escherichia coli (VTEC), compared to 3,217 in 2005, the difference being mainly due to reports from the Czech Republic which accounted for 92% of the increase. A 2000 study of UK outbreaks suggested that more than half of E. coli O157 outbreaks are transmitted by non-foodborne routes. In 1999, Mead et al reporting on gastrointestinal illness in the US estimated that the annual incidence of E. coli O157 infections was 73,480, 15% of which were non-foodborne Who is at risk? Page 3/8

4 Anyone can be infected by E.coli O157. Those most at risk to E.coli O157 are children and the elderly. Symptoms and complications of disease Patients infected with E. coli O157 typically develop acute stomach pain and severe diarrhoea which is watery at first but then becomes bloody. Mild fever and maybe vomiting may also result In some persons, particularly children under 5 years of age and the elderly, the infection can also cause a complication called haemolytic uraemic syndrome (HUS), characterised by renal failure and haemolytic anaemia. HUS is the major cause of acute renal failure in children in Western Europe and North America. HUS develops in up to 10% of patients infected with E. coli O157. The fatality rate of E. coli O157 infection is very variable and depends on the ages of the groups affected. Fatality rates ranging from 1 to 5% have been reported but may be much higher in some institutional outbreaks. In the US it is estimated that 61 people with E. coli O157 infection die each year. Preventing the spread of E. coli O157 infection in the home In situations where there is risk of spread of E. coli O157 infection in the home the following hygiene measures should be rigorously implemented. It must be remembered that E. coli O157 can also be shed by people who have no symptoms both those who have apparently recovered and those who have not developed symptoms. Since the risk of introducing E. coli O157 into the home, either via people, foods or domestic pets is constant and may not be recognised until an outbreak of infection occurs within the family, this means that good day-to-day hygiene including good food hygiene makes sense General Hygiene To prevent transmission of infection from an infected family member (or a family member who may have been exposed to infection outside the home) to other family members or to food: Good hand washing practice is the single most important infection control measure. Hands should be thoroughly washed with soap and running water*. If access to soap and running water is a problem, use an alcohol hand rub or hand sanitiser. In high risk situations where there is an outbreak of E.coli O157 in the home, it is suggested that handwashing followed by use of an alcohol rub/sanitiser should be encouraged. Hygienically clean surfaces in the bathroom and toilet, with particular attention to washbasins, baths and toilet seat and toilet handles. This can be achieved by cleaning with a detergent cleaner followed by thorough rinsing under running water, or when this is not possible, e.g. for toilet seats, toilet flush handles, by use of a disinfectant cleaner. If someone has diarrhoea, toilets should be disinfected after each use. Page 4/8

5 Keep the infected person s immediate environment hygienically clean. The most important surfaces are those which come into contact with the hands, e.g. door handles, telephones, bedside tables and bed frames. To make these surfaces hygienically clean you need to use a disinfectant product. In a busy household it is not always possible to keep hand contact surfaces hygienically clean at all times. This is why it is so important to wash hands as frequently as possible to break the chain of infection. Cleaning cloths can easily spread E. coli infection around the home. They should be hygienically cleaned after each use, particularly after use in the immediate area of the infected person or the bathroom and toilet used by that person. This can be done in any of the following ways: - wash in a washing machine at 60 C (hot wash) - clean with detergent and warm water, rinse and then immerse in disinfectant solution which is effective against E.coli O157 for at least 20 minutes or as prescribed - clean with detergent and water then immerse in boiling water for 20 minutes. - alternatively use disposable cloths. Where floors or other surfaces become contaminated with faeces or vomit, they should be hygienically cleaned at once: - remove as much as possible of the excreta, from the surface using paper or a disposable cloth, then apply disinfectant cleaner** which is effective against E. coli O157 to the surface using a fresh cloth or paper towel to remove residual dirt - apply disinfectant cleaner** to the surface a second time using a fresh cloth or paper towel to destroy any residual contamination. Disposable gloves should be worn if in contact with faeces, and hands should be washed after removing gloves. Clothing, sheets and pillows and linens from the infected person (or carrier) should be kept separate from the rest of the family laundry and should be laundered in a manner which kills any E.coli O157. Either: - for preference, wash at 60 C or above using any laundry product as heat will destroy E. coli O157. Or - wash at 40 C using a bleach-containing laundry (powder or tablet) product. Note: washing at 40 C without the addition of bleach will not destroy E coli O157 Do not share towels, facecloths, toothbrushes and other personal hygiene items with the infected or carrier person. Where young children are ill, or at particular risk: - their handwashing, personal and toilet hygiene may need supervision - nappies should be disposed of safely, or cleaned, disinfected and washed. Contrary to popular perception, the faeces of babies can be highly infectious. Where possible, infected individuals should stay in their own room and use their own facilities, cutlery, crockery etc. Infected people should particularly avoid contact with those who may be more vulnerable to infection, and their personal items. Food and Kitchen hygiene Rigorous food hygiene is important in preventing the spread of E. coli O157 in the home. Where there is an infected or suspected infected person in the home, food hygiene practices should focus on preventing contamination of food, particularly ready to eat foods. Where there is a suspected food source of E. coli O157 in the Page 5/8

6 home, food hygiene practice should focus on containing and destroying the source, and preventing transfer to other foods Infected people should try to stay away from the kitchen and should not prepare food for others. Wash hands after handling food which may be contaminated and disinfect using an alcohol handrub or sanitiser. Wash hands before handling ready to eat foods and disinfect using an alcohol handrub or sanitiser. Hygienically clean all food contact surfaces, utensils and cloths after handling and preparation of raw foods using a disinfectant cleaner which is effective against E. coli O157**. Hygienically clean all contact surfaces, utensils and cloths before handling and/or preparing ready to eat foods. Cook foods thoroughly. Wash any foods such as fruit and vegetables to be eaten raw thoroughly under clean running water. Store foods carefully in a refrigerator or freezer. Ensure that cooked food are kept separate from cooked foods. In an outbreak situation where the primary source has not been identified and removed from circulation, avoid or take particular care with known sources such as beef, hamburgers, cooked meat products, unpasteurised milk and unwashed vegetables. Avoiding infection from visits to farms or other animal exhibits Pay particular attention to hygiene after visiting farms, land occupied by farm animals and avoid contact with animal faeces and places likely to be contaminated with it. Wash hands thoroughly with soap and water immediately after the visit. *How to wash hands: Handwashing technique is very important. Rubbing with soap and water lifts the germs off the hands, but rinsing under running water is also vital, because it is this process which actually removes the germs from the hands. The accepted procedure for handwashing is: Ensure a supply of liquid soap, warm running water, clean hand towel/disposable paper towels and a foot-operated pedal bin. Always wash hands under warm running water. Apply soap. Rub hands together for seconds, paying particular attention to fingertips, thumbs and between the fingers. Rinse well and dry thoroughly. In situations where soap and running water is not available an alcohol- based hand rub or hand sanitiser should be used to achieve hand hygiene: Apply product to the palm of one hand. Rub hands together. Rub the product over all surfaces of hands and fingers until your hands are dry. Page 6/8

7 Note: the volume needed to reduce the number of germs on hands varies by product. In high risk situations where there is an outbreak in the home, handwashing followed use of an alcohol rub/sanitiser should be encouraged One very simple thing which people can do which can significantly reduce the risk of disease is to avoid putting their fingers to their mouth. **Disinfectants and disinfectant cleaners Make sure you use a disinfectant or disinfectant/cleaner such as a bleach-based product, which is active against E. coli O157. For more details on choosing the appropriate disinfectant, see the IFH information sheet Cleaning and disinfection: Chemical Disinfectants Explained. Consult the manufacturers instructions for information on the spectrum of action, and method of use (dilution, contact time etc). For bleach (hypochlorite) products, use a solution of bleach, diluted to 0.5%w/v or 5000ppm available chlorine. Household bleach (both thick and thin bleach) for domestic use typically contains 4.5 to 5.0%w/v (45,000-50,000 ppm) available chlorine. In situations where concentrated bleach is recommended a solution containing not less than 4.5% w/v available chlorine should be used. Bleach/cleaner formulations (e.g. sprays) are formulated to be used neat (i.e. without dilution). It is always advisable however to check the label as concentrations and directions for use can vary from one formulation to another. Other facts about sheets giving information on E.coli O UK National Electronic Library on Infections (NELI) IntegratedCRD.nsf/NeLI_Home1?OpenForm. 2. UK Health Protection Agency Infectious Diseases webw/hpaweb&page&hpawebcontentarealanding/page/ ?p = US Centre for Disease Control and Prevention. Conditions/ IFH Guidelines and Training Resources on Home Hygiene 1. Guidelines for prevention of infection and cross infection the domestic environment. International Scientific Forum on Home Hygiene. Available from: bfbb802574dd003fc2c1?OpenDocument 2. Recommendations for selection of suitable hygiene procedures for use in the domestic environment. International Scientific Forum on Home Hygiene. Available from: h t t p : / / w w w. i f h - homehygiene.org/integratedcrd.nsf/70f1953cec47d d86/24401f 935e57e79e802574e200391c43?OpenDocument 3. Guidelines for prevention of infection and cross infection the domestic environment: focus on issues in developing countries. International Scientific Forum on Home Hygiene. Available from: d e1005a075d?OpenDocument 4. Home Hygiene - prevention of infection at home: a training resource for carers and their trainers. International Scientific Forum on Home Hygiene. Available f r o m : h t t p : / / w w w. i f h - Page 7/8

8 homehygiene.org/integratedcrd.nsf/571fd4bd2ff8f /9aaaeb30 6bb3c50c b4fdc?OpenDocument 5. Home Hygiene in Developing Countries: Prevention of Infection in the Home and Peridomestic Setting. A training resource for teachers and community health professionals in developing countries. International Scientific Forum on Home Hygiene. Available from: b46073e67f d83?opendocument. Further Information 6. The changing hygiene climate: a review of infectious disease in the home and community. International Scientific Forum on Home Hygiene faaa b6e8?OpenDocument 7. The Community Summary Report on Trends and Sources of Zoonoses, Zoonotic Agents, Antimicrobial resistance and Foodborne outbreaks in the European Union in Downloadable from: EFSA/efsa_locale _ htm. 8. Centre for Diseases Control and Prevention. Preliminary FoodNet data on the incidence of infection with pathogens transmitted commonly through food 10 states, 2007 April 11, 2008 / 57(14); Available at: mmwr/preview/mmwrhtml/mm5714a2.htm. 9. Le Baigue S, Long S, Adak GK, O Brien SJ. Infectious Intestinal Disease - it s not all foodborne! PHLS 25th Annual scientific conference, Mead PS, Slutsker L, Dietz V, McCaig LF, Bresee JS, Shapiro C, et al. Foodrelated illness and death in the United States. Emerg Infect Dis 1999;5: Page 8/8